Marine propulsion device



Aug. 22, 1961 H. E. RICHTER MARINE PROPULSION DEVICE Filed July 25, 19601N VEN TOR fiflfyl Zak/5221' ATTORNEYQ United States Patent 7 2,997,015I PROPULSION Harvey'E. Richter, 2801 10th Ave Vero Beacli, Fla.

Filed July 25, 51960, Ser. .No. 44,906

Claims. (Cl. 2115-42) This invention relates to marine ,propulsiondevices, and more particularly to devices of this kind wherein the waterto be acted upon by the propulsion means passes through anopen duct.

There .have been a number of attempts to produce an effective marinepropulsion device using the principle of a rotating helical blade, orvane, advancing along a column of water, much in the nature 'of a nutthreading upon a bolt. lnevery such case, some provision has been madeto enclose within anopen duct the column-of water upon which the vane isto act. However, in many cases, due to the manner of separation of thecolumn from the body of water, or the passage of the water through theduct, excessive turbulence has been created, breaking up the solidity ofthe column to be acted upon and, at the same time, creating resistanceto the forward movement of the propulsion device through the water. Inother embodiments of this principle, the water column has uncontrolledexit from the duct, resulting in cavitation and consequent drag at therear of the devices. .Such arrangements defeat the very purpose of theuse of the principle, by placing a very definite speed limitation on thepropulsion units through building up resistance to the free passage ofthe unit through the water, and impeding the free flow of a solid columnof water through the duct in the unit.

The general object of the present invention is to provide a marinepropulsion device employing the above propulsion principle which will besubstantially drag free.

A more specific object is the provision of such a device wherein anundisturbed core of solid water is cut from the main body while theencircling mass is moved freely, and substantially without disturbancearound the propulsion device.

A further object is to provide a device of this nature which will allowundistorted passage of the core, or column, through a duct of uniformdiameter to maintain solidity of the column and prevent turbulence.

Another object is the provision of a propulsion device which will cut acore, -or column, of sol-id water from the main .body while moving theencircling body freely around the propulsion device, and bringing theencircling body back to the column as a converging cone to impinge upon,and confine, the column -of water emerging from the duct to preventcavitation.

Still another object of the invention is to provide a marine propulsiondevice having rotating vanes within an open duct, with means for dampingany swirling movement imparted to the column by rotation of the vanes toensure the column leaving the duct without spiral and thereby preventsurface turbulence behind the propulsion device.

Yet a further object is the'provision of a device of this nature whichis mounted for rotation about a vertical axis to change the direction ofthrust to permit the device to serve as a steering means for the boat onwhich it is mounted.

Other objects of the invention will appear from thefollowing-description of one practical embodiment thereof, when takeninconjunction with the drawings which accompany, and forrnpart of, thisspecification.

in the drawings:

FIGURE "1 is a vertical section through a marine propulsion deviceembodying the principles of the present invention, parts being shown in"elevation and FIGURE '2 is a front elevation of the device shown in 2FIGURE .1, parts being broken away to show interior structure.

In general, the invention concerns a marine propulsion device having acasing which includes a shell defining an aperture, or duct, of uniformdiameter having as a part thereof a rotatable cylinder carrying vanes ofhelical curvature. A circular edge surrounds the mouth of the duct tocut into the body of water, as the propulsion device moves forward, tocore out a solid column of water upon which the vanes can thread theirway to advance the device along the column, while the encircling body ofwater is directed smoothly around the shell and back as a converging.cone angularly against the surface of the column emerging from the ductto maintain solidarity of the emerging column. Any spiralling of thecolumn imparted by the rotating vanes is stopped before the columnleaves the duct.

Referring to the drawings in detail, the propulsion device 1 is housedwithin a casing 2, which is a two-part casting, the two identical parts.3 meeting along the longitudinal, vertical, medial plane of the unitand held in abutting relation by bolts 4. The casing includes a topmounting flange 5, a suspension post .6, depending from flange 5', ashroud 7 defining a Water duct 8, and a bottom fin v9. A steering drum10 is bolted on top of the flange 5 and secured to the flange by bolts11. The drum is rotatably mounted in a mounting ring 12 (to bedescribed), and the ring is secured to an appropriate portion 13 of theboat on which the propulsion device is to be mounted. It is preferredthat the mounting flange 5 and the post 6 be streamlined in a fore andaft direction so that they will cause as little drag as possible to thefree movement of the device through the water.

As mentioned above, the casing provides a shell, or shroud, 7 whichsurrounds a cylindrical duct 8 through which a column of water to beacted upon by the propulsion device will pass. It is important that theduct be of uniform diameter from end to end, to the end that acylindrical column of water can be cored out of the body of waterthrough which the device is moving and pass freely and undisturbedlythrough the duct, while being confined to maintain its originalsolidity. The shell, or shroud, outer surface 14 curves from fore .toaft, being thicker at its midsection than at its ends. The shell outersurface converges toward the entrance end 15 of the duct, meeting theduct-defining surface of the shroud in a circular knife-edge 16. Therear portion of the shroud converges to the outlet end of the duct tofeather ofi to a thin edge 17. Thus, water surrounding the cored-outcolumn which passes. through the duct will flow outwardly smoothlyaround the shroud shell, substantially Without disturbance orturbulence, and then inwardly along the aft surface to converge insurrounding, confining relation upon the column emerging from the ductto maintain column solidity. 'The shape of the shroud is such thatforward movement of the device will cause the circular knife edge 16 atthe mouth of the duct to cut from, or core out of, the body of water asolid column of water which, due to the uniform diameter of the duct,can pass through the duct without disturbance. The surrounding waterdivided from the core will flow smoothly over the curving surface of theshroud, and smoothly back to surround and confine the column as itleaves the duct to prevent cavitation.

As the column of water passes through the duct, it is acted upon byvanes 18 carried by a rotatable cylinder 19. The inside diameter of thecylinder 19 is equal to that of the entrance and exit ends of the duct'8 and, when the cylinder is in place in the casing, the inner wall ofthe cylinder forms the bridging portion of the duct between the entranceand exit ends. The casing members '3 are hollowed centrally of "theshroud forming a chamber 20.

. 3 v The chamber has recessed seats the ends of cylinder 19. Thechamber is sealed by selflubricating water seals, such as nylon rings 22which seat in grooves 23 in the cylinder seats and bear against thecylinder outer wall adjacent the ends. End thrust of the cylinder istaken by snap in steel thrust rings 24 which lie in recessed seats 25which are stepped inwardly of the seats 21. The inner peripheries ofrings 24 run in grooves 26 in the outer wall of the cylinders. The rings24 are backed by thrust bushings 27 which surround the cylinder and areheld stationary by means of bolts 28 that lock the bushings to thecasing. 1

Four vanes 18 are shown as mounted adjacent the forward end of cylinder19. These are of helical curvature, and are equi-spaced around thecylinder. The vanes emanate from the inner wall of the cylinder andproject inwardly toward the center. They terminate short of the axis ofthe cylinder, however, leaving a center opening 29. The curvature of thevanes and their rotative movement is such that the vanes tend to cut ascrew-like path along the column of water passing through the duct inorder to advance the propulsion device forwardly.

Cylinder 19 is rotated by means of a ring gear 30, bolted to an annularflange 31, projecting outwardly from the cylinder. Gear 30 lies withinthe chamber 20 which is filled with suitable lubricant. Gear 30 is inmesh with a bevel gear 32, mounted on a drive shaft 33 rising verticallythrough the casing and journalled in bearings 34 in the casing. Theshaft will be connected to the boat power plant (not shown). It will beevident that rotation of shaft 33 will cause rotation of the cylinderand vanes and forward movement of the entire unit through the water.

At slow forward speeds of the entire unit and rapid rotation of thecylinder, the water column in the duct 8 will be given a swirling motionso that it would emerge from the duct as a spiralling column withconsequent water upheaval behind the propulsion device if some meanswere not used to prevent it. To this end, four vanes 35 are mounted inthe exit end of the duct. These are straight vanes projecting radiallyinward from the duct surface. These will serve to retard spiral actionand cause the column to leave the duct without turbulence.

The mounting ring 12, mentioned above, rotatably mounts the entirepropulsion device on the boat. The ring has an upstanding flange 36spaced outwardly from the inner peripheral edge of the ring, so that anannual angular seat 37 is formed in which the steering drum rests. Thedrum has a peripheral groove 38 in its rim, and a sealing ring 39 isseated in the groove to bear against the upstanding flange 36 of themounting ring. The steering drum is protected by a cover 40 bolted tothe bolt. The cover has a suitable packing gland 41 to seal around thedrive shaft and prevent water seepage down the shaft.

The steering drum has a spiral groove 42 of two or more helices in itsrim in which the steering cable 43 is laid. This will provide one ormore complete turns of the cable around the drum. The ends of the cableare threaded through outlet thimbles 44 on the drum cover and led to anappropriate wheel, or other steering means (not shown). It will beobvious that pulling upon the cable in one direction or the other willcause the drum to be rotated upon its seat on the mounting ring, thusswinging the entire propulsion device. This will change the direction ofthrust from the water column emerging from the duct 8 and thereby shiftthe boat in the direction of thrust. The propulsion device, therefore,will provide an adequate means for steering as well as propelling theboat.

Assuming that the propulsion device is properly mounted on a boat andthe boat engine, or power plant, is running, movement of the drive shaftwill cause rotation of cylinder 19 with its vanes 18. The movement ofthe spiral vanes will tend to draw the unit forward 21 at the ends tojournal I as the vanes cut into the column of water in the duct, but,due to the initial drag of the boat, the water will be drawn into theduct as the rotating vanes expel water through the duct. As the forwardmotion of the boat increases, the rotating vanes tend to thread theirway along the water column cored out of the body by the forward motionof the unit, and the relative forward speed of the unit and the rotaryspeed of the vanes approaches the point where the vanes actually followa helical path along the column in accordance with their helicalcontour. Water, of course, is incompressible, and the faster an objectis moved through a body of water the more nearly the water acts as asolid. Therefore, the faster the propulsion device is moved forward, themore closely the rotating vanes follow a helical path along the coredout column of water in the duct.

Due to the circular knife edge 16 of the casing at the entrance end ofthe duct which is the precise diameter of the duct, forward motion ofthe device results in an actual coring out of the body of water of asolid column which moves through the duct and upon which the vanes 18act. As the duct is of uniform diameter from end to end, the columnmoves freely through it without restriction or turbulence due toconstrictions or enlargements in the duct with consequent speed andpressure changes. The initial solidity of the column is maintainedthroughout. The surrounding water is divided from the cored out columnwithout turbulence, and flows smoothly over the streamlined outersurface of the shell. The encircling body of water is directed inwardlytoward the column after it passes over the mid-section of the shroud sothat it rejoins the column as the column emerges from the duct, creatinga pressure upon the entire cylindrical column to prevent cavitation andconsequent drag behind the device.

It will be clear from the above, therefore, that the-propulsion deviceof the present invention cores out a solid column of water from the bodyof water through which the unit is passing and maintains the solidity ofthat column through and beyond the duct without expansion or contractionof the column size and without turbulence. At the same time, thesurrounding water is separated from the core and carried smoothlywithout turbulence over the shroud and led at an angle toward the columnas it emerges from the duct to prevent cavitation beyond the unit and tomaintain solidity of the column and undisturbed water behind the unit.This results in a substantially drag free propulsion unit of highefiiciency. As pointed out above, any swirl produced in the column instarting or during acceleration will be removed by passage of the columnalong the stationary vanes 35. By pivotally mounting the unit, the powerthrust can be utilized as a means for steering.

Although the device has been shown as installed for operation by aninboard motor, the propulsion principle and shroud and duct disclosedcan be used with an outboard motor and mount.

While one practical embodiment of the invention has been disclosed, itwill be understood that the details of construction shown and describedare merely by way of illustration and the invention may take other formswithin the scope of the appended claims.

What is claimed is:

1. A marine propulsion device comprising, a casing including a portiondefining a shroud having a duct there through, the duct having anentrance and an exit end and being of uniform diameter and unchangingcross-section from end to end, the shroud having an outer surface gentlycurving convexly from end to end, the shroud outer surface curving tothe duct at the entrance end of the duct to provide a knife edgeperipherally of the entrance end of the duct so that when the device ismoved through a body of water a solid column of water thecross-sectional shape and diameter of the duct will be cored from thebody of water and pass unimpeded through the duct maintaining itscross-sectional shape and diameter, and the encircling water mass willbe led around the shroud, the outer surface of the shroud convergingtoward the exit end of the duct so that the encircling water masspassing over the converging surface will be led at an angle toward acolumn of water emerging from the duct to envelop the column and confinethe column against cavitation, a hollow cylinder having inwardlydirected helical vanes rotatably mounted in the shroud and having aninner surface forming part of the duct, and means outside the duct torotate the cylinder.

2. A marine propulsion device as claimed in claim 1 wherein stationaryvanes are mounted in the duct adjacent the exit end, the stationaryvanes being connected to the casing and projecting radially inward ofthe duct and ex- 1 tending axially of the duct, so that the column ofwater leaving the duct will be without swirl.

3. A marine propulsion device as claimed in claim 2 wherein the helicalvanes of the cylinder terminate short of the longitudinal axis of thecylinder.

4. A marine propulsion device as claimed in claim 1 wherein the helicalvanes of the cylinder terminate short of the longitudinal axis of thecylinder.

5. A marine propulsion device as claimed in claim 3 wherein thestationary vanes terminate short of the longitudinal axis of the duct.

References Cited in the file of this patent UNITED STATES PATENTS945,553 Kovacs Jan. 4, 1910 2,153,055 Weissmann Apr. 4, 1939 2,347,785Lovell May 2, 1944 2,605,606 Pilz Aug. 5, 1952 FOREIGN PATENTS 407,432France Jan. 4, 1910

